1. Field Of The Invention
This invention relates generally to any processing system requiring an inverse two-dimensional transformation of source data, and more specifically to video bandwidth compression systems which use transform and coding techniques to minimize the number of coding symbols required to describe an image.
2. Description Of Prior Art
Two dimensional inverse transforms are ordinarily generated using Fast Fourier Transform (FFT) algorithms, or variations thereof, implemented using either a digital computer or a special purpose processor. Both methods suffer severe limitations in that the signal processing power required to perform two-dimensional inverse transforms in real-time results in a hardware realization which is generally inconsistent with the size, weight, power and cost requirements of many airborne transform decoder applications. This is particularly true in the case of the inverse discrete cosine transform, which is the preferred transform for video bandwidth compression systems, in that in order to achieve the symmetry properties necessary to utilize "fast" algorithms, the size of the transform must be doubled. That is, in order to realize an N-point inverse cosine transform, a 2N-point processor must be implemented resulting in a significant increase in processor complexity.
Accordingly, it is an object of the present invention to provide a two-dimensional inverse transform processor which is organized to accept high speed sampled analog input data and to output the results in a fashion suitable for direct interface with a standard video display monitor.
A further objective is to reduce signal processing complexity, even in the case of the inverse cosine transform, by calculating only the N reconstructed video samples to be displayed on a given video line as opposed to the total N.times.N or N.sup.2 samples (2 N.sup.2 samples for the "fast" cosine transform).
Another object is to accomplish two-dimensional inverse transform processing at a fraction of the cost, size, weight and power required by other two-dimensional inverse transform techniques.